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                            <div style="color:gray; word-break: break-all; font-size:12px;">原英文版地址: <a href="https://www.elastic.co/guide/en/elasticsearch/reference/7.7/norms.html" rel="nofollow" target="_blank">https://www.elastic.co/guide/en/elasticsearch/reference/7.7/norms.html</a>, 原文档版权归 www.elastic.co 所有<br/>本地英文版地址: <a href="../en/norms.html" rel="nofollow" target="_blank">../en/norms.html</a></div>
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<strong>重要</strong>: 此版本不会发布额外的bug修复或文档更新。最新信息请参考 <a href="https://www.elastic.co/guide/en/elasticsearch/reference/current/index.html" rel="nofollow">当前版本文档</a>。
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<span class="breadcrumb-node"><code class="literal">norms</code></span>
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<h2 class="title">
<a id="norms"></a><code class="literal">norms</code><a class="edit_me edit_me_private" rel="nofollow" title="Editing on GitHub is available to Elastic" href="https://github.com/elastic/elasticsearch/edit/7.7/docs/reference/mapping/params/norms.asciidoc">edit</a>
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<p>Norms store various normalization factors that are later used at query time
in order to compute the score of a document relatively to a query.</p>
<p>Although useful for scoring, norms also require quite a lot of disk
(typically in the order of one byte per document per field in your index, even
for documents that don’t have this specific field). As a consequence, if you
don’t need scoring on a specific field, you should disable norms on that
field. In  particular, this is the case for fields that are used solely for
filtering or aggregations.</p>
<div class="tip admon">
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<p>Norms can be disabled on existing fields using
the <a class="xref" href="indices-put-mapping.html" title="Put mapping API">PUT mapping API</a>.</p>
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<p>Norms can be disabled (but not reenabled after the fact), using the
<a class="xref" href="indices-put-mapping.html" title="Put mapping API">PUT mapping API</a> like so:</p>
<div class="pre_wrapper lang-console">
<pre class="programlisting prettyprint lang-console">PUT my_index/_mapping
{
  "properties": {
    "title": {
      "type": "text",
      "norms": false
    }
  }
}</pre>
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<div class="console_widget" data-snippet="snippets/772.console"></div>
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<p>Norms will not be removed instantly, but will be removed as old segments
are merged into new segments as you continue indexing new documents. Any score
computation on a field that has had norms removed might return inconsistent
results since some documents won’t have norms anymore while other documents
might still have norms.</p>
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